1. Field of the Invention
This invention relates to a method for forming a cast article by slip casting, which comprises casting a slip (slurry) of particles such as ceramic particles, metallic particles, etc., and particularly to a method suitable for forming a cast article of complicated shape.
2. Description of the Prior Art
As one of the prior art techniques relating to the present invention, mention can be made of British Patent No. 1,482,436. "Method for Making an Article by Slip Casting".
According to this prior art, a casting mold for a portion having a complex shape is produced using an organic material which is soluble in a solvent, while a gypsum mold is used for a portion having a simple shape. These two molds are then assembled to obtain a desired casting mold.
However, this method does not take into consideration the possibility that a density difference will occur on a green body between the organic portion and the gypsum portion depending upon the shape and size of the resulting cast article and will somehow affect the strength reliability, dimensional accuracy and workability.
There has been proposed a method comprising mixing 0.1 to 4% by weight of an organic polymer with calcined gypsum to make a casting mold, casting a ceramic slip into the casting mold, heating the casting mold together with a green body to 650.degree.-700.degree. C., thereby decomposing the organic polymer in the casting mold and lowering the strength of the casting mold, and then withdrawing the green body therefrom. However, the green body sometimes cracks in the case of forming cast articles of complicated shape owing to expansion and shrinkage by heating and cooling of the casting mold and the green body due to the heating together with the casting mold, a high strength of the casting mold, etc., as in the foregoing prior art